Magnetic disk devices perform magnetic recording in a contact less manner by rotating a magnetic disk at high speed and maintaining the spacing of a magnetic head slider and the magnetic disk with an air film therebetween. In order to record information at high density, it is useful to reduce the spacing of the rotating magnetic disk and the magnetic head slider (referred to as a “flying height”). In current magnetic disk devices, minimum flying height of the magnetic head slider is around 10 nm or less. A magnetic head for recording/reproducing signals is formed on the magnetic head slider using a thin film process, typically. Recent magnetic head sliders may also comprise a built-in heater element for controlling the clearance between the magnetic head and the magnetic disk in the vicinity of the elements of the magnetic head to a high degree of accuracy, and a built-in contact sensor element for detecting contact with the magnetic disk. Combined use of these elements has the function of allowing only the vicinity of the magnetic head near the elements to come safely in proximity to the magnetic disk.
Some magnetic heads comprise only two heads, namely a recording head for recording signals and a reproduction head for reproducing the recorded signals. A system in which a heater element for reducing the spacing of the magnetic head and the magnetic disk is embedded to allow only the vicinity of the magnetic head element to protrude safely is implemented in only some magnetic heads recently. More current heads may also have a built-in contact sensor element for detecting contact with the magnetic disk, in order to minimize the spacing with the magnetic disk. As a result, magnetic heads started out with a total of four terminals being formed on the magnetic head slider, two for elements for the recording head and two for elements for the reproduction head, but current magnetic head sliders have an additional four terminals for the heater elements and contact sensor elements, making a total of eight terminals installed on the magnetic head slider.
The idea of embedding a plurality of heater elements and embedding a plurality of contact sensor elements has also been investigated in order to control the spacing of the magnetic head and the magnetic disk with a high degree of accuracy, so the number of terminals on the magnetic head slider is steadily increasing.
The magnetic head slider is attached to a support component referred to as suspension and the terminals are electrically connected to the suspension using a conductive material such as solder. The increased number of terminals on the magnetic head slider inevitably reduces the terminal area required for connection, and there is reduced quality at the connected sections and a greater amount of work involved in the solder attachment operation, and this causes a reduction in the work yield. Furthermore, increased numbers of terminals lead to an increase in the area of the elements, and the number of magnetic heads per wafer is also reduced and/or limited. This therefore is also a problem from the point of view of production costs.
U.S. Pat. No. 7,589,928 discloses an example of reducing the number of terminals by providing shared terminals for the heater element and the contact sensor element. This example proposes the idea of connecting the heater element and the contact sensor element in parallel or in series to the terminals so that the terminals of the two elements are shared. A passive element is utilized to separate signals in the parallel-connection idea. Specifically, an inductor (coil) is inserted in series with the heater element and a capacitor is inserted in series with the contact sensor element, and use is made of the fact that the signals used by each have a different frequency band.
However, the addition of a new capacitor element and inductance element occupies area on the wafer and the increased degree of integration becomes a problem. If a plurality of heater elements and contact sensor elements are subsequently installed with the aim of controlling the spacing more accurately, it is difficult to further increase the degree of integration. With the series-connection idea, on the other hand, it is difficult to control the respective amounts of current for the heater element, which is intended to provide heating, and the contact sensor element, which is intended to detect signals, and this example only discloses that the two elements are endowed with a layered stricture, and the specific element configuration is not disclosed.